Obama's move to shield some 4 million immigrants here illegally from deportation amounts to "simple common sense," Johnson was to tell the Republican-led House Homeland Security Committee Tuesday in the administration's first testimony on the issue since Obama announced the changes two weeks ago.

"The reality is that, given our limited resources, these people are not priorities for removal," Johnson said in prepared written testimony. "It's time we acknowledge that and encourage them to be held accountable."

Republicans have vowed to stop Obama's moves from taking effect, but how they will do so remained unclear as they returned to Capitol Hill on Monday after a weeklong Thanksgiving break. GOP leadership in the House planned to discuss options in a closed-door meeting with the rank-and-file on Tuesday morning.

The issue is tied in with the need to pass a government funding bill by Dec. 11, or risk a shutdown. Conservatives have been agitating to use any government funding bill to block Obama's moves, and on Monday conservatives on and off Capitol Hill circulated bill language that would stipulate that no money or fees "may be used by any agency to implement, administer, enforce or carry out any of the policy changes" announced by Obama.

White House spokesman Josh Earnest said Monday Obama would veto any government spending bill that undid his executive actions on immigration.

"What the president announced about 10 days ago was entirely consistently with the precedent that was established by previous precedents -- by previous presidents and is well within the legal confines of the law as it relates to prosecutorial discretion," Earnest said.

Others in the Republican Party have warned that including such language would court a government shutdown that could backfire on the GOP, since Obama would be certain to veto it. Lawmakers were casting about for other approaches, including a full-year spending bill for most government agencies combined with a shorter-term measure for departments that deal with immigration.

All agreed they must stop Obama in the wake of November midterm elections where they retook control of the Senate and increased their majority in the House.

"The president's decision to bypass Congress and grant amnesty to millions of unlawful immigrants is unconstitutional and a threat to our democracy," the Homeland Security Committee chairman, Republican Rep. Michael McCaul of Texas, said in a statement. "I will use every tool at my disposal to stop the president's unconstitutional actions from being implemented, starting with this oversight hearing."

Obama's deportation deferral applies to people who've been in the country more than five years and have kids who are citizens or legal permanent residents. He also expanded an existing program that grants work permits and deportation deferrals to immigrants brought here illegally as kids, and reordered law enforcement priorities to focus on new arrivals and people with criminal records.